1. Field of the Invention
The present invention relates to linear motors and, more particularly, to armatures of linear motors.
2. Background Art
A typical linear motor essentially includes N coils or N sets of coils fixedly positioned adjacent each other and a plurality of alternating north and south magnetic poles positioned in spaced parallel relation to the coils. The coils and the plurality of magnetic poles are movable with respect to each other in response to each of the N coils or the N sets of coils receiving selective excitation from an N phase source of electrical power.
In the prior art, each coil of a linear motor is formed from a continuous conductor wound into a suitable form. The cross-sectional area of the conductors utilized to form each coil of a linear motor is selected based on the force the linear motor is designed to generate. Thus, a linear motor designed to produce a greater force will typically have coils wound from wire having a larger cross-sectional area, while a linear motor designed to produce a lesser force has coils wound from wire having a smaller cross-sectional area. It is to be appreciated, however, that the number of turns of coils multiplied by the current flowing therethrough determines the force generated by each coil of a linear motor. Generally speaking, however, wires having a larger cross-sectional area are utilized to form coils of linear motors designed to produce greater force and wires having smaller cross-sectional areas are utilized to form coils of linear motors designed to produce lesser force.
There is a growing need for linear motors of reduced size for assembly of electronic components to electronic assemblies and for mating of fiber optic assemblies. A problem with producing a smaller linear motor, however, is that the desired cross-sectional area of wire utilized to form the coils of these linear motors is smaller than the smallest cross-sectional area of wire conventional state-of-the-art coil winding machines are designed to process. Thus, as the cross-sectional area of the wire utilized to form coils of a linear motor decreases, the difficulty in winding such wire into coils for linear motors increases. This difficulty arises from the physical limitations of coil winding machines to effectively manipulate wires having smaller cross-sectional areas suitable for use in smaller linear motors. Accordingly, there is a need to produce smaller linear motors of reduced size having coils formed from one or more conductors, each conductor having a smaller cross-sectional area than the smallest cross-sectional area of a wire capable of being wound into a linear motor coil by a conventional coil winding machine.
It is, therefore, an object of the present invention to overcome the above problem and others by providing a linear motor having coils formed from one or more conductors having a cross-sectional area smaller than the smallest cross-sectional area of wire capable of being wound effectively with conventional coil winding equipment. It is an object of the present invention to provide linear motor coils formed utilizing a photolithographic process. Still other objects of the present invention will become apparent to those of ordinary skill in the art upon reading and understanding the following detailed description.
Accordingly, we have invented a linear motor comprising a magnet track and a magnet assembly coupled to the magnet track. The magnet assembly has a plurality of side-by-side alternating magnetic north poles and magnetic south poles. The linear motor also includes an armature having a plurality of side-by-side electrically conductive coils formed on an electrically and magnetically nonconductive substrate, preferably a printed circuit board (PCB), which is movably coupled to the magnet track such that the side-by-side electrically conductive coils are positioned and movable in spaced parallel relation to the side-by-side alternating magnetic poles. The substrate includes a plurality of electrically nonconductive layers laminated together. Each layer has a plurality of electrically conductive windings formed thereon in side-by-side relation on at least one surface thereof with adjacent conductive windings of each layer electrically isolated from each other on the layer. Each electrically conductive winding of each layer is positioned in registration and electrically connected with a corresponding electrically conductive winding on each other layer to form one of the electrically conductive coils.
For each coil, the electrically conductive windings on adjacent layers are configured so that magnetic fields produced thereby in response to an electric current flowing through each electrically conductive winding are additive.
The electrically conductive windings of adjacent layers forming one of the electrically conductive coils are connected in series (i) on or adjacent the centers of the electrically conductive windings or (ii) adjacent the perimeters of the electrically conductive windings. The electrical current flows around the central axis of one of the electrically conductive windings of adjacent layers from a perimeter thereof toward the central axis and flows around the central axis of the other of the electrically conductive windings of adjacent layers from on or adjacent the central axis toward the perimeter thereof.
Preferably, each layer includes a plurality of heat transfer vias therethrough. The plurality of heat transfer vias of each layer is positioned in registration with the corresponding plurality of heat transfer vias in the other layers. The windings of each coil positioned in registration are electrically connected via a conductor received in at least one hole and/or via formed in each layer. A plurality of spacers can be positioned between two or more adjacent layers for maintaining the two or more adjacent layers in spaced parallel relation with a gap therebetween. Each layer can be rigid or flexible and the magnet assembly can include at least one magnet coupled to the magnet track. The plurality of side-by-side electrically conductive coils can include an integer multiple of N coils, with every Nth coil electrically connected together.
In operation, selectively energizing adjacent conductive coils with different phases of an N phase electrical source causes the armature to move relative to the magnet assembly.
We have also invented a linear motor comprising a linear armature having a plurality of layers. Each layer has a plurality of electrically conductive windings formed thereon in side-by-side relation on one surface thereof. The plurality of layers is laminated together with a plurality of electrically conductive windings of each layer positioned in registration. Each electrically conductive winding on each layer is electrically connected with corresponding electrically conductive windings positioned in registration therewith on the other layers, and adjacent electrically conductive windings on each layer are electrically isolated from each other on the layer.
Electrically conductive windings in registration on adjacent layers are configured to produce magnetic fields that are additive in response to each of the electrically conductive windings in registration receiving an electrical current therethrough.
The electrically conductive windings in registration on adjacent layers have a common central axis. Around the central axis of each pair of electrically conductive windings in registration on adjacent layers, electric current flows in one of the pair of electrically conductive windings from a perimeter to the central axis thereof, and electrical current flows in the other of the pair of electrically conductive windings from the central axis toward a perimeter thereof. Two or more electrically conductive windings of each layer can be electrically connected.
Lastly, we have invented a motor comprising an armature having a plurality of side-by-side electrically conductive coils formed on an electrically and magnetically nonconductive substrate with adjacent coils electrically isolated from each other. Each coil includes a plurality of electrically conductive windings positioned coaxially and electrically connected so that in response to an electrical current flowing therethrough, each winding produces a magnetic field having the same polarity.